The present invention relates to door closure devices and, in particular, a gravity door closer for providing open and closed detent positions with infinite door positioning therebetween.
In my prior U.S. Pat. No. 3,722,031 granted on Mar. 27, 1973, I provided a door closing and check device for refrigerators and freezers having positively checked open and closed positions wherein a stationary bushing mounted on the cabinet included four upwardly directed camlobes intermeshing with four complementary downwardly directed camlobes as a bushing mounted on the door and rotating within the stationary bushing. The camlobes of the two bushings were located relative to each other to cause the weight of the door to swing the same to its closed position from a partially open position as well as to check and maintain the door at successively wider open positions. The camlobes were in the form of circumferentially undulating surfaces such that only a plurality of distinct door positions were possible. The number of such positions depended on the number of camlobes.
With such a construction I found that it was not possible to attain any variation beyond these discrete positions. Moreover, the weight of the door caused a high loading engagement between the camlobes which tended to severely wear the same after cyclic operation. Therefore, in order to provide the requisite camlobe strength a metal construction, as opposed to a plastic construction, was mandated. However, the mounting of such bushings was by inserting a square shaped shank into a square punched hole in the lower thin sheet metal surface of the door and positioning a serrated hub in a circular opening in the cabinet bracket. The high torque applied to the camlobes of the bushings tended to rotate same within their respective frictional journals. In the case of the sheet metal door, it was found that the sides of the hubs or shanks would cause localized shearing of the surrounding metal and that ultimately the antirotation resistance thereof was destroyed. Similarly, the serrations between the bracket and the hub caused localized shearing and, same, after extended use, the hub became rotatable therewithin. This destroyed the necessary fixed angular positioning.
Another self-closing door closure device is shown in U.S. Pat. No. 3,628,845 (Grimm) issued on Dec. 21, 1971. This device likewise made use of a plurality of intermeshing camlobes in the lower hinge unit. However, the arrangement provided for offsets between the upper and lower hinge axes. The camlobes included converging straight side walls terminating with planar tips. The arrangement was such that two distinct self-closing forces were provided as the door moved from a fully detented open position to a self-biasing closed position. In other words, when the door had rotated from the open position until the camlobe tips contacted, a closing force of a first magnitude was provided. When the side walls interengaged a considerably greater closing force was established. This arrangement, however, likewise did not provide for infinite positioning between distinct detent positions. Moreover, the upper member of the device was pivotally mounted at a screw connection for alignment with a receptacle on the lower surface of the door while the lower member was contained on the cabinet bracket at a non-rotatable connection. While somewhat tending to eliminate the problem of localized shearing at the lower surface, a supplemental receptacle was required which did not provide affirmative alignment of the upper bushing with respect thereto. The lower member was, as in my prior invention, subject to localized shearing and subsequent loosening within the connection such that the fixed detent positions were obviated.
The present invention overcomes the above limitations by providing a pair of telescoping bushings having intermeshing camlobes which provide discrete open and closed positions with infinite positions therebetween. The torque applied at the mountings is resisted by torque arms attached to the cabinet and the door at positions radially spaced from the hinge axis such that no rotation, however limited, is possible thereat tending to cause localized shearing deformation. Between the aforementioned detent positions, the camlobes are provided with interengaging planar walls to establish infinite positioning therebetween.
The above and other features of the present invention will be readily apparent to those skilled in the art, reference being made to the accompanying drawings illustrating a preferred embodiment in which: